266 NATURAL SCIENCE. April, 



Gammarid has huge black eyes : the pair of them almost cover its 

 head, and each is composed of a hundred ocelli or more. The organs 

 of its mouth form a sort of tube with lancets for piercing the skin 

 and sucking the juices of the shark or the whiting or other fish on 

 which it may happen to settle. But the queerest thing about it is 

 that in its great claws the clasping finger seems to be set on at the 

 wrong side. The action of the claw is inverted, as the bending of 

 a man's leg would be if the knees were placed at the back of them 

 instead of the front. In the crustacean, the oddity is produced by the 

 curvature of two little elbow-joints, which really reverses the normal 

 position of the "hand " and "finger." Up to a certain age the animals 

 hold their claws in the ordinary direction. Very few specimens have 

 ever been obtained. These have varied in size from a fifth of an inch 

 to an inch and one-fifth, and have ranged in locality from the Medi- 

 terranean to the borders of the Arctic circle. The three specimens from 

 the neighbourhood of Naples at the disposal of Professor Delia Valle 

 were of medium size. They were all, as far as he could judge, of the 

 male sex. He places them by themselves in a separate species. He 

 goes further. He places them in a separate genus. Yet he admits 

 that in the principal external features they agree with the northern 

 specimens. It does not appear to have entered his mind how ex- 

 tremely improbable it is that there should be two very rare forms, 

 superficially as much alike as twins, but distinguished, according to 

 him, by several subordinate characters of the mouth-organs. On 

 the character of those organs in his own specimens he confesses to 

 having changed his opinion while his book was being printed. He is 

 aware that all the northern specimens hitherto described have been 

 females or young. He well knows, nay, he himself emphatically and re- 

 peatedly insists, that in the Amphipoda not only slight but important 

 distinctions are often due only to differences of age or sex. In this 

 particular kind of Gammarid it has been already shown that there is 

 at least one remarkable variation between the adults and the young. 

 Nevertheless, on the strength of trivial measurements arrived at by 

 the dissection of minute organs, upon personal observation of only 

 one sex in specimens of uncertain age, Delia Valle goes out of his 

 way to set up a new species and a new genus, such as, judging by 

 his usual practice, he would assuredly have cancelled had any other 

 naturalist been so venturesome. Any other naturalist might have 

 done it without reproach. It is the common fault. Only to Delia 

 Valle himself was such a liberty not permissible, since the whole plan 

 of his volume is one long protest against it. Perhaps he was moved 

 by a tender consideration for the dwindling limits of natural history, 

 which he has dispeopled of so many genera and species, and thought 

 it necessary to restore the balance by a few of his own making. 

 When once on the path of creation, he gives play to his inventive 

 genius, and establishes a new suborder of Amphipoda. In this he 

 at first intended to place the form which has just been discussed. 



